Though this is a question I often ask my ten-year-old son, it is actually useful at the easel.  It's one of those questions that's so obvious it gets overlooked.  What am I thinking that is making me mix this color?  What am I thinking this shape will do for the focal point?  Once my daughter was watching me paint, and, since this made me feel self-conscious, I thought I would let her in on the process.  So I explained what I was doing in each step and why.  When I stepped back and looked after a few minutes of this, I was amazed.  My painting looked so much better!  "Being intentional" I suppose is the same idea.